Assuming that you can use your camera for such purposes, all you need to do is go to this website and download Skype.

http://www.skype.com/intl/en-us/get-skype/on-your-computer/windows/

System requirements
◦PC running Windows® 2000, XP, Vista or 7, both 32- and 64-bit operating systems. (Windows 2000 users require DirectX 9.0 for video calls).
◦Internet connection – broadband is best (GPRS is not supported for voice calls).
◦Speakers and microphone – built-in or separate.
◦For voice and video calls we recommend a computer with at least a 1GHz processor, 256 MB RAM and of course a webcam.
◦For best quality on group video beta calls, we recommend that calls include up to five people.
◦For group video calling everyone on the call needs Skype 5.0 for Windows plus webcams. You'll also need a high-speed broadband connection (we recommend sustained 512 kbit/s downlink or more) and a computer with a 1 GHz processor (minimum) or Core 2 Duo 1.8 GHz (recommended).

If your camera is not suitable then you will need something like these http://www.pixmania.co.uk/uk/uk/754/195/xx/104/9/criteresn.html

This video should help you understand how to download, install and run Skype. http://www.youtube.com/watch?v=ssLj_89FHKI&feature=related Watch it before doing anything. Don't worry too much about any techi speech, just concentrate on what they do.
Then if you are happy with it, have a go at doing it for real.